Technologic advancements allowing the early, nonsurgical diagnosis of ectopic pregnancy prompted the initiation of medical therapy for ectopic pregnancy. The medical regimens became popularized without efficacy assessment or rigid criteria for the limitations of usage. In May, 1999 the Reproductive Medicine Network initiated a pilot protocol to 1) compare the efficacy of single dose methotrexate and multiple dose methotrexate in the treatment of ectopic pregnancy and 2) determine the limitations of usage for each protocol. The Principal Investigator of this application is the principal author of the prospective randomized trial for this project, a project well suited for the multicenter network because of its importance to public health and its need for a large number of subjects due to the expected small differences in efficacy. As a Reproductive Medicine Network member for 10 years, the Principal Investigator and Co-Investigator have had a major role in the two completed network studies. We contributed 225 subjects or 24 percent of the total, to the project, "Randomized Treatment of Unexplained Infertility", with 32 percent of the resultant pregnancies.' A comparable number were recruited for the "Evaluation of Semen Parameters in Fertile Males". Our institution is especially well positioned to contribute to the newest initiated network-wide study, "The Evaluation of the Luteal Phase in Fertile and Infertile Women" because the faculty at Baylor is responsible for 3 hospitals (1 public; 2 private) in the nation's largest concentration of health care facilities-the Texas Medical Center. In part, for this reason, the ectopic pilot study initiated only 6 weeks ago, is already 40 percent completed and ahead of the recruitment schedule. In addition, one of the largest male reproductive units (Dr. Larry Lipshultz) complements our 3 Reproductive Endocrinologists, 2 Reproductive Geneticists, and 4 Gynecologists. Our experience in the Reproductive Medical Network has enabled us to collaborate with the other clinical centers and data collection center in designing prospective clinical trials to test hypothesis relevant to clinical medicine. We acknowledge and accept first hand the loss of autonomy necessary to represent the collective wisdom of the several institutions participating in a multicenter effort. However, the gains are substantial to the scientific community -and long awaited in our field in particular.